This invention provides a novel process for chlorinating cyanuric acid to produce alkali metal dichloroisocyanurates without the concommitant formation of nitrogen trichloride or other chloroamines.
Dichloroisocyanurates are well-known materials which are widely used as a source of available chlorine in solid bleaching, sanitizing and detergent compositions. The sodium and potassium salts are the most widely used in laundering compositions because they are very soluble and easily removed by rinsing.
Exemplification of one prior art process producing sodium dichloroisocyanurate is disclosed in U.S. Pat. No. 3,035,056. In this process, sodium dichloroisocyanurate is produced by chlorination of trisodiumisocyanurate with gaseous chlorine which results in the production of both sodium dischloroisocyanurate and sodium chloride. In contrast, U.S. Pat. No. 3,035,057 produces potassium dichloroisocyanurate by reacting trichloroioscyanuric acid with tripotassium isocyanurate.
U.S. Pat. No. 3,083,144 discloses another process for producing sodium dichloroisocyanurate by chlorinating cyanuric acid with sufficient chlorine and sodium hypochlorite or sodium hydroxide to produce solid dischloroisocyanuric acid at a pH value of from 1.5 to 3.5 and at a temperature from 5.degree. to 45.degree. C. wherein the mole ratio of said alkali to cyanuric acid is from 1.90:1 to 2.1:1 in a first aqueous medium, and neutralizing the solid dichloroisocyanuric acid with sodium hydroxide in a second aqueous medium at a pH from 6 to 7 to form sodium dichloroisocyanurate dihydrate particles which are subsequently separated and dried.
While these processes are effective for producing sodium or potassium dichloroisocyanurates, they require carefully controlled procedures for carrying out the chlorination and neutralization reactions to maximize product yields as well as to minimize the production of dangerous said products, such as nitrogen trichloride. Slight changes in the amount of chlorinating material and/or the alkali necessary to carry out the reaction can cause rapid changes in pH values which changes often result in cyanuric acid ring degradation.